I am not surprised. IMHO, MailChimp as a product has not been making sense for email marketing for a while now. I moved out of it around 6 months back.
Now, in the light of all these changes, it is going to be a wake-up call for a lot of other users especially the ones whose core use case is indeed email marketing.
Btw until I read this article - I was not aware of the details around "Additional Charges"!